Doesn't work after upgrading past 5.1

Unfortunately, `alias_method_chain` has been deprecated in Rails 5.1. so if you are attempting to run this in a < 5.1 app you will get:

```/bundle/ruby/2.6.0/gems/resque_manager-3.3.13/lib/resque_manager/overrides/resque/worker.rb:85:in `<class:Worker>': undefined method `alias_method_chain' for Resque::Worker:Class (NoMethodError)```